D0054 - A Case of Type II Autoimmune Pancreatitis in a Patient Treated With Pembrolizumab Adjuvant Therapy

Leo Boneschansker, MD, PhD, Avinash Kambadakone, MD, Oladapo Yeku, MD, PhD, Martha Pitman, MD, Motaz Qadan, MD, PhD, Brenna Casey, MD, Yasmin G. Hernandez-Barco, MD
Massachusetts General Hospital, Boston, MA

Introduction: Immune checkpoint inhibitor (ICI)-therapy causes GI toxicity but its association with mass-forming Type II AIP has not been described. While pancreatic manifestations of ICI-toxicity are known, it does not include mass-forming AIP. This case demonstrates development of a worrisome pancreatic mass during ICI-therapy which was not amenable to steroid treatment due to potential adverse oncological outcomes. We describe the pathological and imaging features of this entity so that others may consider this diagnosis in the future.

Case Description/Methods: A 59-year-old female was diagnosed with stage IIIC clear cell ovarian cancer. Treatment included optimal cytoreduction to no evidence of disease, adjuvant carboplatin/paclitaxel and bevacizumab, followed by two year bevacizumab/pembrolizumab maintenance to prevent recurrence. After 15 months on pembrolizumab, patient had developed mild epigastric pain and diarrhea, and restaging positron emission tomography scan showed a FDG-avid lesion in the pancreatic head (Figure). MRI showed a 3.5cm hypoenhancing mass in this region without pancreatic duct dilation. Labs included lipase of 1014, normal liver function tests, tumor markers and IgG subclass levels. Endoscopic ultrasound (EUS) with fine needle aspiration demonstrated atypical cells and fine needle biopsy (FNB) showed features consistent with chronic pancreatitis with few plasma cells. A diagnosis of Type II AIP versus ICI-pancreatitis was made and patient was monitored with close surveillance imaging. Follow up CT showed increased size of the pancreatic mass to 4 cm and new biliary duct dilation. Repeat EUS-FNB showed pancreatic parenchyma with cellular fibrosis, prominent periductal lymphohistiocytic and eosinophilic inflammation, and ductal cells positive for PD-L1 consistent with Type II AIP (Figure). Steroids were not given due to concern for adverse oncological outcome. Repeat imaging following completion of her ICI-therapy showed complete resolution of the mass and her symptoms improved.

Discussion: To our knowledge, we describe the first case of mass-forming Type II AIP in the setting of ICI-therapy. While imaging and histology were consistent with Type II AIP, it is possible that this represents a new entity of ICI-mass forming pancreatitis. Here we demonstrate that she was able to complete her ICI therapy while managed with short-interval imaging studies and pancreatic function monitoring. Additional studies are needed to determine the role of ICI-therapy in mass-forming AIP.



Disclosures:


Leo Boneschansker, MD, PhD, Avinash Kambadakone, MD, Oladapo Yeku, MD, PhD, Martha Pitman, MD, Motaz Qadan, MD, PhD, Brenna Casey, MD, Yasmin G. Hernandez-Barco, MD. D0054 - A Case of Type II Autoimmune Pancreatitis in a Patient Treated With Pembrolizumab Adjuvant Therapy, ACG 2022 Annual Scientific Meeting Abstracts. Charlotte, NC: American College of Gastroenterology.